Secure Digital (SD) and Secure Digital High Capacity (SDHC) flash memory cards are commonly used in devices like digital cameras, laptop computers, and camcorders. Their high capacity and low cost can be attributed to die shrinks as the pace of semiconductor technology moves forward.

SD cards have a maximum capacity of 4GB, while SDHC cards can go up to 32GB. Although this may seem like an extreme size, high-definition camcorders and digital photography enthusiasts have been pushing for a new format with higher maximum capacities and faster transfer speeds.

The industry answered earlier this year at the 2009 Consumer Electronics Show with the Secure Digital eXtended Capacity (SDXC) format, which has a maximum theoretical capacity of 2TB and could eventually reach speeds as high as 300 MB/s.

Although there were many promises made, there aren't really any SDXC cards that you can buy. A large part of the problem is due to the old chicken and egg paradigm; no one wants to produce a large, expensive, niche product if there are no SDXC card readers that can support the new format.

The SDXC format allows for backwards compatibility, meaning that readers should be able to use older SDHC, SD, and MMC cards. Development work has been slow, and the big push for products supporting SDXC won't occur until next year. The first wave of products will show up at this year's CES.

Many of those products will integrate SDXC card readers made by JMicron through a PCIe bus. JMicron's SDHC readers are commonly used in the industry and integrated into laptops, mobile phones, and digital cameras.

Did they really need use the second letter of extended to make it SDXC? Seriuosly, what's wrong with SDEC? Did someone already use SDEC for something, or did they just have a focus group of 18 year olds...

In computing, "extended" has been referred to in acronyms by the letter "X" for years, though usually because "E" had already been used for something else which actually began with the letter "E".

We had EGA (Enhanced Graphics Array) and the later XGA (Extended Graphics Array). There was also EMS (Expanded Memory) and XMS (Extended Memory). There may well be other examples but those are two obvious ones.

Essentially the word "Extended" is now pretty much associated with "X" rather than "E". So for me Secure Digital Extended Capacity just seems right as being SDXC. And of course, "X" is a lot sexier than "E" in an acronym :)